AIDS stands for Acquired Immunodeficiency Syndrome. AIDS is a life-threatening disease caused by the Human Immunodeficiency Virus (HIV). AIDS was first reported in the United States (US) in June 19811981. AIDS damages our body’s immune system. In the last 2525 years or so, AIDS has spread all over the world, killing more than 2525 million people. This article will discuss all the details related to AIDS.

AIDS is an important topic in the chapter “Human Health and Diseases” in NCERT Biology books for Class 12. NCERT books are structured in a way that makes it easier for the students to understand the concepts related to the topic better. Embibe offers a range of study materials that includes PDF of NCERT books, previous year question papers and solution sets. Students can follow these study materials to enhance their preparations significantly.

AIDS: Details

AIDS is an immunodeficiency disease, the last stage of HIV infection is referred to as AIDS. It occurs when the immune system of the body is damaged because of the virus that interferes with the ability of the body to fight against the infections.

AIDS is acquired at any phase during the lifetime of an individual, indicating that it is not a congenital disease (a disease that is present at or before birth). The word ‘syndrome’ in AIDS meaning ‘a group of symptoms’.

What is HIV?

1. AIDS is an immunodeficiency disease caused by a retrovirus called HIV. This retrovirus has RNA as its genetic material, which can replicate through DNA copies.
2. HIVs have an amazing ability to convert their RNA genomic material into double-stranded DNA (RNA \(\to \) DNA) by a process called reverse transcription inside the host cell. These DNA copies can be integrated randomly into one of the chromosomes of host DNA.
3. This process of forming DNA from RNA is possible because HIV carries the gene for the reverse transcriptase enzyme. The copying of RNA to DNA is done by the enzyme RNA-dependent DNA polymerase or reverse transcriptase.
4. HIV is also called HTLV-III (Human T- Lymphotropic Virus Type – III) or LAV (Lymphadenopathy Associated Virus) also. These abbreviations stand for information denoting a virus that attacks white blood cells (T- lymphocytes) in the human blood.

AIDS: Symptoms

People infected with the HIV virus remain apparently well even after the infection. They may not show any physical symptoms of illness for a long time which may vary from a few months to several years (\(5 – 10\)years). But after some time, the body may respond in many ways:

1. Sweating at night and tiredness.
2. Weight loss and loss of appetite.
3. Swollen lymph nodes and fever. Sometimes the person may suffer from cough and fever and may face difficulty in breathing.
4. Decreased count of blood platelets that may lead to haemorrhage and fever.
5. The person’s body becomes susceptible to other infections like pneumonia, tuberculosis and certain cancers.
6. The nervous system may get damaged, mainly affecting the brain.It may lead to memory loss, partial paralysis, loss of coordination, mental disorder and loss of ability to speak and think.

AIDS: Causes

The ways by which AIDS disease is spread are as follows:

1. When a person has sexual contact with an HIV-infected person.
2. By sharing infected needles as in the case of drug abusers and blades or razors.
3. By blood-to-blood contact as in blood transfusion.
4. From an infected mother to a foetus through the placenta.

Important Fact!

Although the AIDS virus has been found in tears and saliva, no instance of transmission from these body fluids has been reported. So, there is no danger of infection with the AIDS virus by casual social contact or by sharing cups, towels, or food. Also, there are no known cases of AIDS transmission by insects like mosquitoes or pests.

HIV Infection: Progression

Without treatment, HIV infection advances in stages, getting worse over time. There are three stages of HIV infection:

1. Acute HIV infection
2. Chronic HIV infection
3. AIDS

Acute HIV Infection

It is the earlier stage of HIV infection, which generally develops within \(2 – 4\) weeks after infection with HIV. In this stage, HIV multiplies rapidly and spreads throughout the body. HIV attacks and destroys the T-lymphocytes of the immune system. The level of HIV in the blood is very high, which greatly increases the risk of HIV transmission. A person may experience significant health benefits if they start taking HIV medicines during this stage.

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Chronic HIV Infection

It is the second stage of HIV infection (also called asymptomatic HIV infection or clinical latency). During this stage, the rate of multiplication of HIV is very low. The person may not have any HIV-related symptoms, but it is possible to transmit HIV to others during this stage. The transmission can be prevented by taking HIV medicines. Without medicines, this infection usually advances to AIDS in 10 years or longer.

Is AIDS the last stage?

AIDS is the final, most severe stage of HIV infection. At this stage, HIV would have severely damaged the immune system due to which the body can’t fight against opportunistic infections like pneumonia, tuberculosis, cancer, etc. A person with AIDS has a high HIV load and can transmit HIV to others very easily. Without treatment, people with AIDS typically survive about \(3\) years.

Which Group of People are at High-risk of Getting Infected with HIV?

The high-risk groups who become infected with HIV are as follows:

1. Homosexual men
2. Bisexual men (who have both homosexual or heterosexual partners) and individuals who have multiple partners
3. Male and female intravenous drug users
4. An individual who requires repeated blood transfusions
5. Children born to an HIV infected mother

Diagnostic Test for AIDS

When HIV enters the bloodstream, it begins to attack the white blood cells (T- Lymphocytes). In response to these viruses, substances called antibodies are produced in the body. These antibodies can be detected by a specific blood test called ELISA, usually two weeks to three months after infection. However, Western blotting provides the most accurate results.

Detection of AIDS by ELISA Test

The Enzyme-Linked Immunosorbent Assay (ELISA) test is the most widely used method for detecting the presence of HIV antibodies. In \(1984\), ELISA was developed to determine whether an individual is carrying HIV or not.

Western Blot Assay

Western blot assay is conducted for confirmation of cases that show positive ELISA test. This process helps to detect specific HIV proteins (antigens) for which antibodies are present in the serum of ELISA-positive patients.

Process of Infection by HIV

The process of infection by HIV are as follows:

1. HIV attaches itself and binds with the receptors on the plasma membrane of the T – helper cells (macrophages or CD4 cells).
2. HIV then enters the cell and uses a special enzyme called reverse transcriptase to make a DNA copy called cDNA of its genetic material.
3. This single strand of DNA replicates and produces double-stranded cDNA.
4. Now, this double-stranded viral DNA integrates into the host cell’s DNA, where it directs the production of viral RNA.
5. Each strand of viral RNA brings about the synthesis of viral proteins, which combine with the RNA strands to give rise to many new viruses.
6. These new viruses are then released from the host cell before the host cell dies. So, T- lymphocytes act like an HIV factory.
7. The new HIVs formed attack more T- helper cells, replicate and produce more viruses.
8. This process is repeated that leads to the progressive decrease in the number of T- helper cells.

AIDS: Preventive Measures

AIDS is a progressive disease and there is no cure to it as of yet. However, medical science has evolved to the point where the progression of the disease can be slowed down significantly. There is no vaccine invented to prevent AIDS. Most individuals with severe infection die within a few years from other infections. However, it is preventable. People can be educated on the following things so as to help ignorant people from becoming victims.

1. Insist on the use of fresh new blades at the barber’s shop. Common razors should not be used.
2. Sexual contact with unknown people should be avoided.
3. Only disposable needles and syringes should be used.
4. During any blood transfusion, transfused blood should be tested.
5. Advocating safe sex and promoting regular check-ups for HIV in susceptible populations.

However, by taking HIV medicines called Anti Retro-viral Therapy (ART), people with HIV can live long and lead healthy lives and prevent transmission to their sexual partners. National AIDS Control Organisation (NACO) and other Non-Governmental Organisations (NGOs) are doing a lot to educate people about AIDS.

Summary

AIDS is considered to be one of the challenging public health issues. But there is a global commitment to stop new HIV infections and ensure that everyone with AIDS has access to HIV treatment. New global efforts have been undertaken to fight against this disease, particularly in the last decade. The number of people with new HIV infections has reduced over time. \(1\)st December is declared as World AIDS Day since \(1988\). It is an international day dedicated to raising awareness for the AIDS pandemic.

Frequently Asked Questions (FAQs) on AIDS

Frequently asked questions related to AIDS is listed as follows:

Q.3. How is AIDS caused?
Ans: AIDS is caused by the Human Immunodeficiency Virus (HIV). This virus can be transmitted in the following ways:
1. By sexual contact with an infected person.
2. By sharing infected needles, blades, or razors.
3. By blood-to-blood contact as in blood transfusion.
4. From an infected mother to a foetus through the placenta.

Q.4. What are the three stages of HIV infection?
Ans: The three stages of HIV infection are:
1. Acute HIV Infection
2. Chronic HIV infection
3. AIDS

Q.5. How does the AIDS virus work?
Ans: The AIDS virus or HIV attacks and destroys the white blood cells (specifically T-lymphocytes also called CD 4 cells) of a person’s immune system, which helps in producing the antibodies against the attacking pathogen.

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